Modular electron-discharge tube



April 28, 1959 c. KARABATS ETAL MODULAR ELECTRON-DISCHARGE TUBE 2 SheetsSheet 1 Filed April 16, 1956 IIDIII! Christopher Korobcns James D Le Von INVENTOR.

April 28; 1959 c. KARABATS ET AL 7 2,884,553

MODULAR ELECTRON-DISCHARGE TUBE Filed April 16, 1956 2 Sheets-Sheet 2 Fig. 5;

Chris'i'opher Kumbcfis James D. Levcm INVENTOR.

United States Patent MODULAR ELECTRON-DISCHARGE TUBE Christopher Karabats, Lexington, Mass., and James D.

LeVan, Nashua, N.H., assignors, by mesne assignments, to Sanders Associates, Inc., Nashua, N .H., a corporationzof: Delaware Application April 16, 1956, Serial-No. 578,345

4Claims. (Cl. 313-254) This" invention relates to modular devices for electronics. More particularly, the invention relates to modular, space-discharge tubes.

Inathe construction of modular packaging for electronic components as described in National Bureau of Standards Technical News Bulletin Number 11, volume 37, November, 1953, it has been a problem to provide compatible space-discharge tubes. As described and illustrated in NBS. Bulletin Number 11, such modules are typically formed: of a. plurality of congruently stacked, spaced, ceramic wafers having perimetrically disposed indentations formed therein. The waters have metallic conductiye paths aflixed thereto and are supported in place by riser wires or conductors disposed in the wafer indentations. The indentations are coated with silver which is caused to adhere to the riser wires as, for example, by soldering or. brazing.

In the prior art space-discharge tubes, particularly electron-discharge tubes, are formed primarily from glass envelopes and metal or phenolic bases- The electrodes typically are vertically supported by metallic conductors which extend from the base of the tube. Such tubes do not. operate satisfactorily at temperatures in excess of 185 C. Furthermore, these tubes are extremely susceptible to mechanical shock and vibration. Additionally, these tubes are not readily integrated into modular units.

It: is, therefore, an object of the invention to provide an: improved. modular, space-discharge tube operable at temperatures in excess of 600 C.

A further object of the invention is to provide an improved modular, space-discharge tube capable of withstanding a high degree of mechanical'shock and vibration.

A still further object of the invention is to provide an improved modular, electron-discharge tube having uniform electron emission.

In accordance with the invention, there isv provided a modular space-discharge tube. The tube comprises a plurality of stacked ceramic wafers having metallic conductive paths. affixed thereto. A heater element issecured between a pair of adjacent wafers. An electrode frame, having an annular channel centrally formed therein, is disposed adjacent the heater and secured to a wafer and: one of the conductive paths. This frame has perimetrically disposed perforations to confine the area of the. electrode heated. An electrode disc is so disposed in and. so secured to the channel as to enable radial expansion and contraction of the disc within the channel in. one plane while the disc is rigidly secured against movement in the plane normal to it.

Alsoin accordance with the invention, there is provided aimodular space-discharge tube comprising a plurality of stacked ceramic wafers having metallic conductive paths afiixed thereto. A heater means is secured between a pair of adjacent ones of the wafers. An electrode is disposed adjacent the heater and has a center in the form of a disc. This electrode. has. an. annular flange, secured to one of the wafers and one of the conductive paths.

I cent wafers 10d and 102.

The electrode also has a metallic ring having a slot alongthe interior perimeter for supporting the center in the slot mechanically and electrically, the metallic ring being connected to the flange by a plurality of curved tabs. The curved tabs minimize heat transfer from the center to the flange and provide freedom for radial expansion of the center in the plane of the center while rigidly supporting the center against movement in planes normal to the center plane.

For a better understanding of the present invention, together with other and further objects thereof, reference is made to the following description taken in connection with the accompanying drawings and its scope will be pointed out in the appended claims.

In the drawings:

Fig. 1 is a perspective view of an electron-discharge tube embodying the invention;

Fig. 2 is a perspective view, in exploded form and partially in section, of an electron-discharge tube embodying the invention;

Fig. 3 is a sectional view of the embodiment in Fig. 1;-

Fig. 4 is a partially sectional, perspective detail view of the cathode structure of the embodiment in Fig. 1;

Fig. 5 is a perspective, detail view, partially in section, of a modification of the cathode in Fig; 4; and

Fig. 6 is a sectional, detail view illustrating the as sembly of the cathode of Fig. 5 and the heater for energizing the cathode.

Description of the discharge tube in Figs. 1-4

Referring now to the drawings and with particular reference to Figs. 1-4, there is here illustrated a modular, spacedischarge tube. While the embodiment illustrated and described herein is particularly directed to an electrondischarge tube, the term spacerdischarge tube is employed to include both vacuum and gas discharge tubes in which either negative or positively charged particles are transmitted through space. The electron-discharge tube here illustrated is a twin-triode having a heater 13, a pair of cathodes 14, a pair of control grids 17, and a pair of anodes 16 contained within and supported by a plurality of congruently stacked, ceramic wafers. Thus, in detail, and referring particularly to Fig. 2, the tube comprises a plurality of congruently stacked, ceramic wafers 10a-10h; each having a metallic conductive path 11 affixed thereto. The inner wafers 10b-10g, inclusive, have circular holes 12 centrally formed therein. The end wafers 10a and 10h enclose the ends of the tube and seal the discharge space formed by the holes 12. The heater element 13, disposed at approximately midpoint axially and diametrically of the holes 12,, is secured between the middle pair of adja- The cathodes 14, in the form ofja pair of disks, are individually secured between different ones of the pairs of wafers 10c, 10d and 102, 10f. As shown more particularly in Fig. 4, the cathodes 14 have perimetrically, here circumferentially, disposed perforations 19a to confine the area in which the cathode is heated. In a manner similar to that of the cathodes, the control grids 17 in the form of perforated saucer-like disks are secured between different ones of the pairs of wafers 10b, 10c and 101, 10g. The anodes 16 are disposed between end Wafers and the adjacent inner wafers, one between the wafers 10a and 10b and the other between the wafers 10g and 10h. The electrodes. are flanged to enable peripheral securing between pairs of wafers in. contact with a conductive path 11 on each of these wafers to provide means for making external connections to the electrodes and are shaped, as shown, to provide. a suitable spacing between electrodes.

The wafers have perimetrically disposed indentations 15 to provide means for external connections. The. conductive paths 11 are terminated in and connected to selected indentations '15 for etfe'cting a desired matrix of connections. The indentations 15 are preferably silvercoated and solder-filled and a plurality of riser wires 18 are disposed therein and, for example, soldered or welded in place. The tube is assembled by eifecting ceramic-to metal seals between the wafers and the electrodes. Such ceramic-to-metal seals are well known; for example, see Materials Technology for Electron Tubes by Walter H. Kohl, published by Reinhold Publishing Corporation, 1951, Chapter 16, pages 403-421. The tube being of modular form may also be mounted as an extended portion of a module with common riser connections being made to the module and the modular tube.

Particularly important features of the present invention are the annular channels 19 and perforations 19a formed in the channels of the cathodes 14. The effect of the channeling and the perforations is to concentrate the heat in the center of the cathodes. This produces a uniform temperature gradient across the-center of the cathode and, consequently, uniform emission. It has the further advantage of reducing the input power required to heat the cathode as well as reducing cathode end heat losses, thereby reducing hot-spot temperatures. The increased uniformity of heat distribution tends to further reduce localized hot-spots and greatly enhances the life of what is generally recognized to be the weakest element in electron-discharge tubes.

1 One form of the ceramic tube embodying the present invention is .875 square and .28" in height. The volume of a twin-triode tube embodying the present invention can be less than .12 cubic inch as compared with 6 cubic inches for standard receiving tubes. Such a tube, however, is capable of operating at temperatures in excess of 600 C. as compared with the conventional limitation to 185 C. Furthermore, tubes embodying the present invention are capable of dissipating in excess of 8 watts of power as compared with conventional tubes which are limited to 1 watt.

Description of cathode in Figs. and 6 In Figs. 5 and 6 there is illustrated a modification of the cathode structure as used in the embodiment of Fig. 1. The modified cathode 20 has an annular flange member 21 which is secured between the wafers in the manner used for the cathode 14 of Figs. 14. A plurality of curved tabs 22 extend radially inward to an annular channel member 23 which supports an electron emitting cathode disk 24. The member 23 may be spot-welded to the. disk 24 at a plurality of circumferential locations but preferably is only spot-Welded or otherwise secured at one point, as indicated at 25, to provide a positive electrical contact. The flange 21, tabs 22 and channel 23 provide orifices to reduce the conduction path for heat emanating from the disk 24. Since member 23 and cathode 24 are secured at only one point, the lack of rigid assembly thereof permits expansion and contraction of the disk 24 within the confines of the channel of the member 23 without deformation or buckling of the disk 24. This is highly beneficial, since, due to the close spacing of the cathode grid and anode electrodes, any buckling of the cathode might cause shorting of the cathode to the adjacent grid.

While applicant does not intend to be limited to any particular shapes, sizes or materials of parts in the embodiments of the invention just described, there follows a set of dimensions and materials for the more important parts which have been found to be particularly suitable for a twin-triode amplifier tube of the type represented by Figs. 1 and 2:

Heater 13.75 long by .026 in diameter, formed from .002" tungsten wire with .002 aluminum oxide insulation;

Cathodes 14-outer diameter of flange .350; outer di Control grids 17-flange outer diameter .350"; grid outer diameter .280"; diameter of grid mesh .240"; height, .035; materialgn'd mesh .001" thick nickel; ferrule .002 thick nickel;

Anodes 16-flange outer diameter .410"; flange inner diameter .330; outer diameter of anode disk .280"; height .055; materialnickel .005" thick;

Spacing between end wafers and anodes 16-.053;

Anodes 16 to control grids 17 spacing-.018";

Control grid 17 to cathode 14 spacing--.005"; and

Total thickness of the two cathodes 14 and heater 13 structure.040".

It will be apparent from the above description that while the structure presented by the present invention has more immediate application to electron-discharge tubes, it is suitable for all modular, space-discharge tubes. It will be further apparent from the above description that the discharge tube of the invention fulfills a critical need in an area where other modern devices such as transistors,

amplifiers, capacitive amplifiers and conventional dis-' various changes and modifications may be made therein' without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

' metallic ring having a slot along the interior perimeter for supporting said center in said slot mechanically and" electrically and connected to said flange by a plurality of curved tabs for minimizing heat transfer from said center. to said flange and for providing freedom for radial ex-' What is claimed is:

l. A modulator, space-discharge tube, comprising: a

ductive paths aflixed thereto; a heater element secured between a pair of adjacent wafers; an electrode frame having an annular channel centrally formed therein, disposed adjacent said heater and secured to a wafer and one of said conductive paths, said frame having permetrically disposed perforations to confine the area of the electrode heated; and an electrode disk so disposed in and so secured to said channel as to enable radial expansion and contraction of said disk within said channel in one plane:

ing an annular channel centrally formed therein, disposed adjacent said heater and secured to a wafer and one'of said conductive paths, said frame having perimetricallyj disposed perforations to confine the area of the cathode:

heated; and a cathode disk so disposed in and so secured to said channel as to enable radial expansion and con-'v traction of said disk within said channel in one plane while said disk is rigidly secured against movement in the plane normal to said one plane.

3. A modular, space-discharge tube, comprising: plurality of stacked ceramic wafers having metallic conductive paths affixed thereto; a heater means secured between a pair of adjacent ones of said wafers; and an electrode disposed adjacent said heater and having a center in the form of a disk, an annular flange secured to oneof said wafers and one of said conductive paths, and a pansion of said center in the plane of said center while rigidly supporting said center against movement in planesnormal to said center plane.

4. A modulator, space-discharge tube, comprising: a plurality of stacked wafers having metallic conductive paths afiixed thereto; a heater means secured between a pair of adjacent ones of said wafers; and an electrode disposed adjacent said heater and having a center in the form of a disk, an annular flange secured to one of said wafers and to one of said paths, and a hollow, metallic ring having a slot along the interior perimeter for supporting said center in said slot, said ring being mechanically and electrically connected to said center at a point and mechanically and electrically connected to said flange by a plurality of curved tabs for minimizing heat transfer from said center to said flange and for providing freedom for radial expansion and shifting of said center in the plane of said center, while rigidly supporting said center against movement in planes normal to said center plane.

References Cited in the file of this patent UNITED STATES PATENTS Brian Aug. 12, 1947 Halstead et al. Jan. 18, 1949 McIntosh Mar. 8, 1949 Stutsrnan Apr. 26, 1949 McCullogh Jan. 17, 1956 Sorg Mar. 27, 1956 FOREIGN PATENTS Great Britain July 25, 1951 

